The present invention relates to detergent compositions and more particularly to heavy duty liquid detergent compositions for laundering, stain and spot removal and general purpose cleaning.
In recent years heavy duty liquid detergent compositions have become very popular for home laundry use, industrial uses, and in diluted form for hand dishwashing. These compositions offer many advantages over powdered detergent products such as ease of use, no dust or caking, no spillage from torn packages, etc. Generally, heavy duty liquid detergents contain anionic and non-ionic surface-active agents, phosphates and polyphosphates, soil suspending and dispersing agents, optical brighteners, colorants and perfume. The surface-active agents, which furnish the detergent action, are generally of the linear alkylaryl sulfonate type (anionic), and mono- and dialkanolamides of long chain fatty acids (non-ionic). Phosphates and polyphosphates are added as effective and efficient soil-suspending agents and to disperse the soil to mitigate against its redeposition on the washed fabrics. Since phosphates are alkaline and corrosive to aluminum parts in washing machines, alkali metal silicates are added as corrosion inhibitors to minimize the corrosive effect of phosphates.
Recently, however, the use of phosphates and polyphosphates in detergent compositions has been discouraged and even banned in many areas for ecological considerations. Non-phosphate-containing detergents are available, but these contain inorganic substances such as sodium carbonate and sodium sulfate as phosphate replacements. They may also present ecological hazards and in addition their detergency is usually less than phosphate-containing compositions.
Another problem associated with detergent compositions containing inorganic salts is that a precise balance of ingredients must be effected to achieve stability on long standing or at low temperatures.
In recent years a new class of non-ionic surface-active agents has been made available for use in liquid detergent compositions. To a great extent they have replaced the alkanolamides of long chain fatty acids as the non-ionic component of detergents. These products are synthetic alcohols with carbon chain lengths of 12-15, which are then reacted with ethylene oxide to produce so-called ethoxylated alcohols containing from 3 to 12 moles of ethylene oxide per mole of alcohol. These products are low-foaming with good water solubility and have excellent detergent properties. They lend themselves well to the formulation of non-phosphate detergents, although they are equally useful in phosphate-containing compositions.
However, even the most efficient current commercial heavy duty liquid laundry detergents lack the ability to remove completely or substantially completely certain types of soil from cotton or cotton-synthetic blend fabrics and to substantially prevent some soil redeposition in the washed fabric, despite the addition of soil-suspending agents to the composition. The most common type of soil found on wearing apparel is sebaceous soil, which arises from the secretion of natural oily ingredients from the skin. This soil is particularly adherent to cotton and cotton blends and is difficult to remove during the laundering cycle. Many compositions have been offered as pre-treatments before laundering, but none has proved substantially successful.